The Transport Accident investigation Commission (TAIC) today published its Final Report on the accident in which a Eurocopter EC120-B lost control in flight and crashed into the beach at Kekerengu river mouth, North of Kaikoura, on 15 December 2020.
On this fine day for flying, the helicopter was approaching to land on a grassed area near the beach-side café at Kekerengu. The helicopter slowed as it turned towards the beach and headed downwind for a low-level pass to inspect the intended landing area. It yawed suddenly, descended with uncontrolled increasing rate of yaw, and was destroyed when it crashed onto the beach. Impact forces far exceeded the recommended level of crash protection for aircraft.
On board were the pilot and spouse, their two children and a child’s friend. The two adults received fatal injuries and all three children were seriously injured. The children survived largely because they were smaller and lighter than the adults.
TAIC’s Chief Investigator of Accidents, Naveen Kozhuppakalam, says the accident happened at a critical phase of flight for any helicopter – the transition from cruise to hover.
“In helicopter flight, the main rotor blades go one way, so the fuselage wants to go the other. Pilots use the tail rotor to control which way the helicopter points -- the slower the airspeed, the more the pilot needs to adjust the tail rotor.
“In this accident, it’s likely the pilot was focusing more on the landing site and preparing for landing, than on controlling the tail rotor.
“The pilot’s experience level – newly qualified as a private pilot – was the key factor in their inability to regain control after being startled by the sudden yaw.
“Typically, experienced pilots instinctively anticipate the need to prevent yaw, while less experienced pilots tend to anticipate less, react more, and they need to work harder on the pedals to keep the helicopter on the right heading.
“It may seem obvious but it bears repeating; the number one priority for all pilots when flying is to fly the aircraft. A pilot qualification, licence or aircraft-type rating does not in itself confer expertise.
“Pilots need to be familiar with the aircraft they are flying and their own capability as they gain experience, and the increased risks of flying at low level, and monitor the performance of their aircraft accordingly.”
The Commission identified no new sector-wide safety issues, so the final report makes no new recommendations.
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Notes for editors
- What yaw is: The helicopter’s blades go one way, so the fuselage wants to go the other way. Pilots use the tail rotor to control which way the helicopter points. The main rotor is driven from a single point that generates a torque reaction, which causes the fuselage to yaw or turn in the opposite direction to the main rotor. For the EC120-B, the main rotor rotates clockwise when viewed from above. The fuselage would therefore yaw left when power was applied. The greater the power, the greater the torque effect. To manage this, a pilot uses the tail rotor to generate a counter force. The tail rotor thrust is controlled through the tail rotor pedals, also called anti-torque pedals.
- Uncontrolled yaw - this accident: A video recording held by the Commission shows that the rate of yaw increased from when it first started to turn and continued until it descended from view behind bushes. The yaw rate for the first full turn was about 90° per second, increased to over 120° per second for the second full turn, approaching 180° per second for the last half turn before the helicopter went from view.
- Other potential issues: There were no medical or mechanical issues identified that may have contributed to the loss of control.